A wireless terminal with multimode (Global System for Mobile Communications (GSM)/Wideband Code Division Multiple Access (WCDMA)/Code Division Multiple Access (CDMA)/Long Term Evolution (LTE)) and receive diversity technologies is a key development direction of the industry in the future. Limited by a size of the wireless terminal, a spacing between multiple antennas on the wireless terminal is close to each other. If working frequency bands of the multiple antennas overlap, mutual coupling is caused between the multiple antennas, affecting radiation efficiency of the antennas. For example, in a diversity antenna system of the wireless terminal, a coupling effect of electromagnetic waves objectively exists between a main antenna and a diversity antenna. This coupling effect is especially strong for a low frequency diversity antenna system. An analysis of main reasons is as follows: In one aspect, the main antenna and the diversity antenna share a metal ground, the metal ground is a main radiator of the main antenna and the diversity antenna, and relatively strong common ground coupling exists between the main antenna and the diversity antenna; in another aspect, spatial coupling exists between the main antenna and the diversity antenna, and in the case of a low frequency band, the foregoing spatial coupling is relatively strong due to a small spacing between the main antenna and the diversity antenna. When the main antenna works in a transmission state, due to the coupling effect between the main antenna and the diversity antenna, the diversity antenna becomes an apparatus for “receiving and consuming” electromagnetic waves radiated from the main antenna, which reduces the radiation efficiency of the main antenna.
Currently, a method is to install a resonant device onto a metal ground between antennas, so as to change current distribution on the metal ground when the antennas are in a working state, thereby improving isolation between the antennas. However, because the resonant device is surrounded all by metals, and is a non-open structure, a part of radiated energy of the antennas is converted into heat inside the resonator due to a conduction and dielectric loss, and the radiation efficiency of the antennas is reduced.